Sealing mechanism for packaging machines



Nov. 5, 1963 M. NATELLl SEALING MECHANISM FOR PACKAGING MACHINES Filed Jan. 9, 1961 FIG. 4..

FIG. 1.

INVENTOR MflE/O N4 7544/,

tates atent fitice 3,19,?64 Fatented Nov. 5, 1963 3,109,764 SEALING MECHANISM FOR PACKAGING MACHINES Mario Natelli, Emerson, N..l., assignor to Kleer-Pak Machinery & Packaging, Inc., Newark, N..I., a corporation of New Jersey Filed Jan. 9, 1961, Ser. No. 81,341 15 Claims. (Cl. 156582) This invention relates to sealing rings for forming the longitudinal or side edge seals on package tubes formed in continuous high speed packaging machines. One type of such machine, by way of example, is shown in the Lewis Patent No. 2,657,510, November 3, 1953. The invention relates more particularly to improvements in the construction and design of such sealing rings calculated to overcome serious defects in prior art constructions.

The rolls carrying such rings and the rings themselves are subject to a substantial degree of heat. This, and other causes as well, has tended to cause distortion, warping and other irregularities in the rings or rolls with the result that the opposing or mating rings do not continuously meet in operation against a web of packaging material, thereby causing gaps in the seal of the continuous web, with consequent leakage from the finshed package.

The sealing rings of the prior art were permanently fixed to their supporting rolls, with no provision for relative movement between them. Thus, any warpage or distortion in ring or roll which brought about a failure of the opposing rings to meet at any point in a pressure engagement with any portion of the web of packaging material, caused a gap rather than a seal to be formed in the web at the point where the rings failed to meet, and this caused leakage in the finally formed package.

A principal object of the present invention is to overcome this defect.

Another object of the invention is to provide, in a pair of mating sealing rings, one which can move radially, or float with respect to its support when in pressure engagement with a web of packaging material, under the pressure of the opposing, mating ring.

Another object is to provide a novel support for said rings to simplfy their installation on a heating roll or shaft.

A further object is to provide means for resiliently supporting said sealing rings for movement about said support.

Other objects will appear from the disclosure in the accompanying specification and drawings, in which:

FIGURE 1 is a plan view of a pair of heat rolls carrying heat sealing rings according to this invention, for simultaneously forming the longitudinal or edge seals on a web of tubing;

FIGURE 2 is a vertical sectional view of FIGURE 1 taken along the line 2-2 thereof, in the direction of the arrows;

FIGURE 3 is a horizontal sectional view taken along the line 3-3 of FIGURE 2;

FIGURE 4 is a modification showing, in section, another manner of mounting the sealing rings on the heater rolls; and

FIGURE 5 is an elevation of a web of packaging material after it has passed through the sealing rings, showing the longitudinal or edge side seals.

The invention comprises a pair of heated juxtaposed rolls or shafts 10, a which have electrical heating elements 11 inserted therein. These rolls and their associated parts perform the functions of forming the longitudinal edge or side seals of packages made, for example, according to the disclosure of the Lewis Patent No.

2,657,510, November 3, 1953, but do so in an improved manner designed to overcome the objections to the prior art apparatus as discussed above. Each of these juxtaposed rolls 10, 10a carries one or more mating sealing rings which firictionally engage the packaging material web W as it is fed past said rolls and form the edge or side seals thereon as indicated in FIGURE 5.

The sealing rings on the right hand side of FIGURE 1 comprise sleeves 12 which are fixed to the shaft 10a by means of one or more set screws 13. Each sleeve has a pair or ring sealing surfaces 12a, 12b, which may be knurled in any suitable design or left plain as desired, and in use they are mated with an opposite pair of sealing surfaces carried by the opposing shaft or roll 10. These rings are made of rigid, heat-conductive material.

The opposing sealing rings on the shaft 10 comprise sleeves 14 having a hub portion 15 and a flange portion 16. A series of stud bolts 17 extend axially of the sleeve and are carried by the flange 16 at radially spaced points. The sleeve is adapted to be fixedly mounted on the roll or shaft 10 by means of one or more set screws 18. A pair of sealing rings 19, 19a are mounted over the hub portion 15 with a spacing washer 20 between them. The bore of each ring at 21 is slightly greater than the external diameter of the hub 15 so as to allow the ring to move freely in a radial direction with respect to said hub. The same is true of the holes 22 in the rings where they fit over the studs 17. While the difference between the bores 21, 22 of the rings and the external diameters of the hub 15 and bolts 17 are not critical, it is preferred that the bores be of the order of greater". It is important that the bores be sufficiently greater to allow free radial movement of the rings 19, 19a, with respect to the hub 15 under pressure of the opposing mating rings of the sleeve 12 when the shafts are rotated during the package forming process. Thus, the rings 19, 19a can move or float around the hub of the sleeve, finding their own centers as they move about. The shaft 10 is also prefer ably supported in end bearings (not shown) which are adjustable towards and away from the axis of the shaft 10a to give a greater range of movement to the shaft 10. This is necessary when operating on web material of varying thickness.

The rings are retained on the hub and bolts 17 by means of nuts 23 and are yieldably urged and supported against the flange 16 by means of spring members 24 interposed between the nut and ring.

The heater roll 10a is supported at each end in bearings (not shown) which are fixed and immovable. The heater roll 10 is supported by bearings (not shown) which are adjustable in the direction of the arrows A in FIGURE 2. In operation, the space between the mating rings of each roll are adjusted to permit passage of the webs W between them under pressure, the floating sealing rings 19, 19a adjusting themselves quickly and easily so as to maintain pressure contact with the web at all times, regardless of any warpage, distortion or irregularity which may occur in the rolls or rings through heat or other causes. This assures a constant longitudinal seal along the web of the packaging material and avoids the gaps which cause leaks.

It will be noted that the uppermost rings in FIGURE 1 are single rather than double. The single ring is used at each outside edge of the web W to form the outer edge seal W The double, intermediate rings form intermediate double rows of seals as shown in FIGURE 5 for the side edges of adjacent packages. The web W between the intermediate seals is appropriately slit either before or after the seals are formed, and cross seals W are formed as desired. As many packages may be formed side by side, as in FIG- URE 5, as are desired, simply by adding sealing rings 3 to the heater rolls as indicated, and limited only by the length of the rolls.

A modification of the invention is shown in FIGURE 4, wherein the heater roll is formed with an integral flange 16a and the floating sealing ring 190 is mounted against this flange in the manner heretofore described.

. In operation, the websof material W to form envelopes to receive a product are fed into themachine and between the rolls 10, 10a where the longitudinal edge seals W W are made, the mating heated rings pressing against the webs to seal them together at the point of contact, the floating rings. adjusting themselves to the fixed rings according to the exigencies of the situation. After passing through these sealing rings, the web is subjected to another operation where the cross seals W are formed. A product is dropped into the envelope thus formed and the envelope is then given its final cross seal to complete a package, in a manner well known in the art.

While a preferred'form of the invention has been shown and described, it will be understood that variations and changes in construction and design may be made without departing from the spirit of the invention as defined by the appended claims.

What is claimed is:

1. Heat sealing mechanism for packaging machinery comprising parallel spaced shafts, means for heating at least one of said shafts, and sealing rings on each shaft in substantial alignment and opposing relationship with one another and adapted'to frictionally engage packaging material between them for pressure sealing purposes when said shafts are rotated, said rings being relatively narrow with respect to said shafts, the rings on one of said shafts being fixed and immovable thereon, the rings on the opposing shaft being radially movable thereon under'the pressure of the opposing ring, both rings being of rigid, heat-conductive material, and means for supporting said radially movable ring on said shaft.

2. Heat sealing mechanism for packaging machinery comprising parallel spaced shafts and sealing rings on each shaft in substantial alignment and opposing relationship with one another and adapted toengage packaging material between them for pressure sealing purposes when said shafts are rotated, means for heating said shafts, said rings being relatively narrow with respect to said shafts, the rings on one of said shafts being fixed and immovable thereon, the rings being in heat-conductive relationship with said shafts, [the rings on the opposing shaft having an internal diameter sufficiently greater than the diameter of its supporting shaft to be radially movable thereon under the pressure of the opposing ring so that saidmovable ring can find its own center during rotation, and means for supporting said radially movable ring on said shaft.

3. A mechanism according to claim 1, in which one of said shafts has a sleeve fixed thereon, and said movable ring is seated on said sleeve and is radially movable with respect to said sleeve, said sleeve having means for retaining said ring.

4. A mechanism according to claim 1, in which one of said shafts has a sleeve fixed thereon, and said movable ring is radially and yieldablymovably supported with respect to said sleeve.

5. A mechanism according to claim 1, in which one of said shafts has a sleeve fixed thereon, said sleeve having.

is radially movablewith respect to said sleeve, said sleeve 7 having fastening means for yieldably supporting said ring against said sleeve.

7. Heat sealing mechanism for packaging machinery comprising parallel spaced shafts and a sealing ring on each shaft in substantial alignment and opposing relationship .with one another and adapted to engage packaging material between them for pressure sealing purposes when said shafts are rotated, the ring on one of said shafts being fixed and immovable thereon, a sleeve on said opposing shaft opposite said fixed ring, means for fixing saidsleeve to said shaft, a sealing ring seated on said sleeve the internal diameter of said ring being of sufficiently greater diameter than the external diameter of said sleeve to allow said ring to find its own center thereon under pressure of the opposing ring, and means for retaining said ring on said sleeve.

8. A mechanism according to claim 7, in which the sleeve has a flange and the sealing ring is 'yieldably retained against said flange.

9. A mechanism according to claim 7, in which the sleeve has a flange and stud bolts are supported in said flange, said movable sealing ring being yieldably supported on said stud bolts.

10. A heat sealing mechanism for pressure sealing of heat sensitive packaging materials comprising a shaft and means for heating same, a sleeve adapted to seated on said shaft in heat-conductive relationship, and a heat sealing ring on said sleeve in heat-conductive relationship therewith, said ring being supported on said sleeve for limited radial and axial movement with respect thereto.

11. A mechanism according to claim 10, in which the ring is yieldably supported for said limited movement on said sleeve.

' 12. A mechanism according to claim 10, in which said.

sleeve is flanged and said ring is seated against said flange, and means carried by said flange to yieldingly urge the ring against the flange.

13. A mechanism according to claim 10, in which the sleeve is flanged, stud bolts extending axially of said flange, said ring being seated on said stud bolts, and spring means on said bolt yieldably supporting said ring against said flange.

14. In a packaging machine, the combination comprising a pair of juxtaposed heated rolls, heat sealing rings on said rolls in heat-conductive relationship therewith, said rings being in alignment with one another for sealing heat and pressure sensitive materials between them when said rolls are rotated, the axis of the rings on one of said rolls being fixed against movement with respect to its roll, the axis of the respective opposing ring on the other of said rolls being free to move radially with respect to said roll under pressure of the opposing fixed ring.

15. In a packaging machine, the combination comprising a pair of juxtaposed rolls, a ring on each roll, said rings being disposed to apply pressure to a web passing therebetween, one of said rings being fixed to its respective roll and being radially non-movable with respect thereto, the other of said rolls being provided with flange means and the other. of said rings being disposed between said flange means and being radially displaceable with respect to its respective roll, said other ring being held in position on said roll by frictional grip of said flange means thereon, whereby circumferential distortion of either of said rings is compensated by self-adjusting radial movement of said other ring effected by mutual pressure of said rings on each other.

References Cited in the file of this patent UNITED STATES PATENTS 437,208 Kinney Sept. 30, 1890. 2,262,325 Kendall Nov. 11, 1941 2,374,504 Salfisberg Apr. 24, 1945 2,385,583 McLauchlan Sept. 25, 1945 2,466,030 Landau Apr. 5, 1949 2,893,468 Fieroh July 7, 1959 

1. HEAT SEALING MECHANISM FOR PACKAGING MACHINERY COMPRISING PARALLEL SPACED SHAFTS, MEANS FOR HEATING AT LEAST ONE OF SAID SHAFTS, AND SEALING RINGS ON EACH SHAFT IN SUBSTANTIAL ALIGNMENT AND OPPOSING RELATIONSHIP WITH ONE ANOTHER AND ADAPTED TO FRICTIONALLY ENGAGE PACKAGING MATERIAL BETWEEN THEM FOR PRESSURE SEALING PURPOSES WHEN SAID SHAFTS ARE ROTATED, SAID RINGS BEING RELATIVELY NARROW WITH RESPECT TO SAID SHAFTS, THE RINGS ON ONE OF SAID SHAFTS BEING FIXED AND IMMOVABLE THEREON, THE RINGS ON THE OPPOSING SHAFT BEING RADIALLY MOVABLE THERON UNDER THE PRESSURE OF THE OPPOSING RING, BOTH RINGS BEING OF RIGID, HEAT-CONDUCTIVE MATERIAL, AND MEANS FOR SUPPORTING SAID RADIALLY MOVABLE RING ON SAID SHAFT. 